From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68A75ECDE43 for ; Mon, 5 Nov 2018 13:39:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FB6120866 for ; Mon, 5 Nov 2018 13:39:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FB6120866 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-security-module-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728094AbeKEW7h (ORCPT ); Mon, 5 Nov 2018 17:59:37 -0500 Received: from mga11.intel.com ([192.55.52.93]:2318 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726723AbeKEW7h (ORCPT ); Mon, 5 Nov 2018 17:59:37 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Nov 2018 05:39:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,468,1534834800"; d="scan'208";a="103526625" Received: from jsakkine-mobl1.tm.intel.com (HELO localhost) ([10.237.50.180]) by fmsmga004.fm.intel.com with ESMTP; 05 Nov 2018 05:39:47 -0800 Date: Mon, 5 Nov 2018 15:39:47 +0200 From: Jarkko Sakkinen To: Tadeusz Struk Cc: jgg@ziepe.ca, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] tpm: add support for partial reads Message-ID: <20181105133947.GA21757@linux.intel.com> References: <154084273717.29396.1021945733871865594.stgit@tstruk-mobl1.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <154084273717.29396.1021945733871865594.stgit@tstruk-mobl1.jf.intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Mon, Oct 29, 2018 at 12:52:17PM -0700, Tadeusz Struk wrote: > Currently to read a response from the TPM device an application needs > provide big enough buffer for the whole response and read it in one go. > The application doesn't know how big the response it beforehand so it > always needs to maintain a 4K buffer and read the max (4K). > In case if the user of the TSS library doesn't provide big enough > buffer the TCTI spec says that the library should set the required > size and return TSS2_TCTI_RC_INSUFFICIENT_BUFFER error code so that the > application could allocate a bigger buffer and call receive again. > To make it possible in the TSS library, this requires being able to do > partial reads from the driver. > The library would read the 10 bytes header first to get the actual size > of the response from the header, and then read the rest of the response. > This patch adds support for partial reads, i.e. the user can read the > response in one or multiple reads, until the whole response is consumed. > The user can also read only part of the response and ignore > the rest by issuing a new write to send a new command. > > The usecase is implemented in this TSS commit: > https://github.com/tpm2-software/tpm2-tss/commit/ce982f67a67dc08e24683d30b05800648d8a264c > > Signed-off-by: Tadeusz Struk > --- > Changes in v2: > - Allow writes after only partial response is consumed to maintain > backwords compatibility. I do not understand what this bullet means. Do you deny writes somehow? /Jarkko